1. Field of the Invention
The present invention relates to cover restricting mechanisms and, particularly, to a cover restricting mechanism for a foldable electronic device such as a mobile telephone, an electronic notebook, and so on.
2. Discussion of the Related Art
With the development of the technologies of wireless communication and information processing, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Foldable electronic devices are particularly welcome by consumers for their convenience.
Generally, foldable electronic devices have most of the electronics in one housing, called the main body. The other housing, called the flip cover, normally contains fewer electronic components than the main body. Other foldable electronic devices have all the electronics in the main body, with the flip cover containing no electronics. Various types of hinge assemblies are used to join a main body and a flip cover of a foldable electronic device, so that the flip cover can unfold and fold relative to the body. Manufacturers are constantly seeking to reduce the volume, size and weight of such foldable electronic devices. Also, it is desirable for the hinge assembly coupling the main body with the flip cover to have a long working lifetime.
A modularized hinge assembly generally has moving parts such as a cam member having a cam surface, a cam follower having a cam follower surface, a spring, a shaft, and a housing. The cam member, the cam follower, and the spring are placed around the shaft, and then received in the housing, thereby being held together in a unified structure. The housing is secured to the main body of the foldable electronic device, and the cam member engages with the flip cover of the foldable electronic device. The cam member and the cam follower always contact each other by engagement of the cam and follower surfaces, these surfaces being forced together due to the action of the spring. When opening the flip cover, the flip cover is opened by hand, which makes the cam member rotate along with the flip cover. At the same time, the cam member urges against the cam follower, making the cam follower movable along the shaft and compressing the spring. When the cam member rides over a convex portion of the cam follower, the flip cover is opened to a predetermined angle. Releasing the flip cover, the cam follower urges against the cam member, under the force of the spring, and makes the cam member rotate, thus making the flip cover open fully.
In the above-described hinge assembly, when the flip cover is opened to a predetermined angle, the flip cover rotates to a predetermined position. This rotation occurs due to the engaging relationship of the cam follower and the cam member, such engagement being maintained under the force of the spring. However, the abrupt force of the spring of the hinge assembly has a large impact on the flip cover, which may damage the flip cover and/or decrease the working lifetime of the flip cover. Such a negative influence on the operation of the flip cover would expectedly reduce the working lifetime of the foldable electronic device, overall. In addition, many foldable electronic devices need to be opened to other positions such as 150° or 160° positions. This angle requirement means that the main body of the foldable electronic device itself needs to be specially designed in order to limit the maximum opening angle of the flip cover. This designing takes up valuable “real estate” on the main body, increases the complexity of the manufacture of the main body, and increases the overall volume and weight of the mobile phone. Furthermore, each time the flip cover is opened, it impacts the main body. The main body is liable to become worn or damaged due to such impact, thereby shortening the working lifetime of the mobile phone.
What is needed, therefore is to provide a cover restricting mechanism that overcomes the above-described problems.